FranciscoMota:
Hi!I am working on a project and I would like to know if it is possible to determine a gas concentration that is flowing inside a tube with a laser and a receptor.
Is it possible? Or is there any other way to do this without disturbing the flow?
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Anything is possible is you can describe the physics/chemistry and if there are sensors for the process. Building one's own sensor is possible, but this forum generally does not engage in speculation. This is where experimentation mu st fall into your role.
If you tell us that a laser pointed across a volume of air to a type of sensor will produce a voltage output on the sensor ranging from , then we can tell you that the Arduino has the ability to monitor analog voltages between 0V and the Vref (generally 5V but can be lower ... such as using the internal 1.1V source.)
There are also software techniques to get that 2^10 analog step up by 1 or sometimes even 2 more order of magnitude... but there are trade-offs.
I would think that cooking oil that is emitted as a vapor and pulled through an exhaust would be sensitive to a particular wavelength. A photocell that is sensitive to that same particular wavelength would seem to be a reasonable approach to measuring average concentration across an area of the duct. However, I suspect the flow of air and particulates would not be uniform across a rectangular (or circular) exhaust pipe due to turbulent air flow through the duct... suggesting a series of sensors may be required.
Ray